Thread-cutting die



6;]. PIHL, (NOW BY JUDlClAL CHANGE OF NAME C11 PIEL).

THREAD cunme'ms. APPLICAT ION FILED APR. 18,1919. RE NEWED JULY 10,1920.

1,416,059, 1 Patented Ma '16,1922.

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CARL J'. IPIHL, (NOW BY JUDICIAL CHANGE OF NAMECARL J, PIER) OE BOSTON,MASSACHUSETTS. i

THREAD-CUTTING DIE.

intense.

Specification of Letters Patent. P te ted 31 ,16 1922 Application filedApril 18, 1919, Serial No. 291,375. Renewed. July 10, 1920. Serial No.39 5,38 1.

To all whom it may concern:

Be it known that I, CARL J. PIHL, (now by judicial decree named. CARL J.Irnn) a citizen of the United States, and resident of Boston, countyofSuii'ollr and Commonwealth of Massachusetts, have invented certain newand useful Improvements in h dC n Dies, of which the following is afull, e

The objects of this invention are to produce a die constructed insections in such a manner that when in use the sectionscan be accuratelypositioned and maintained in such positionby positively reliable holdingmeans which permits the ready disassembling of the die sections for thepurpose of regrindingr A further object is to so form and construct thesections comprising the complete die that there will be provided ampleclearance beyond each cutting edge so as to avoid the dragging orrubbing of the internal edge of each section againstthe cylindricalsurface of the work formed by the cuttin edge.

For holding purposes I make the die in ear, and exact specification.

sections which are held together as a unit by a clip orencirc-led holderof novel construction which facilitates the positive alignment of thedie sections with one another while holding them together as a unit forhandling when outside ofthe die stock.

Another feature of the invention consists in the peculiar form andconstruction due to a method of constructing the die sections so thatthere will be provided ample clearance back of each cutting edge on theinside surface of the die.

These and other features of the invention will be particularly explainedin this specification'and willbe defined in the claims hereto anneged.

In the accompanying drawings I have illustrated the preferred form ofthe invention together with certain modifications thereof in which IFigure 1 is a main assembled'view showing the assembled die o'perativelyheld in the die stock. a

Figure 2 is a detail viewfof the sectional die assembled for insertioninto the die stock.

Figure 3 is a detail view of a modified formof the holding clip.

F gure 4 s an assembled view of the die sections enclrcled' by an'a11nular holding 0 1p.

ferred form of holdingclip.

Figures 6, 7, and'8 show modified forms of holding clip both separatedand assembled characterized by arectangular formatlon- I Figures 9 and10 are enlarged views showing the method of cutting forming I thesectional die. l

I will first describe the method of constructing/the die sections whichform the 5 providedvwith four pairs of setscrews 7 an'd' 8 which arethreaded radially so as to pro ect inward through said holding ring.

The screws are then adjusted so that the straight or radial edges ofeach quadrant are pos tioned w1th one such edge extend- Figure 5 is adetached view of preing beyond the center while theother edge I isretracted the "samedistance away from the center. In this way all fourquadrants? are offset along both radial edges infrelation, to the centerof the holding ring, such offset being a symmetrical by reason of thefact that one side edge is retracted from the center while the otherside edgeis advanced beyond it. 1

When all foursections have been thus sesurely offset in the holding ringa hole is centrally bored concentric with thebe'nter of theholdingring'andthe interior surface of said centralhole is then tapped to formthe proper threads, After the boring and tappin operation four smallerholes corresponding to the number of the sections are boredsymmetrically so as to, intersect" each pair of adjacent edges of thedie and the periphery of said; central hole as shown in Figure 10. Ifpreferred howeverjfthe boring of the small symmetrically arranged holes11 may precede the threading or tapping of the central hole. When soboron and threaded the die sections are ready for assemblage and use.

F or such assemblage i prefer to employ a clip such as is shown inFigures 1, 2 and 5 which is a flat spring metal ring '13 having rightangle flange 20 extending inwardly from one side edge and having twoinwardly projecting hooks at the ends of the ring.

By using this construction the tour sec tions can be readily insertedfrom the open or unfianged side of the clip and forced down against theretaining flange or lip 20 with strong pressure so as to secure positivealignment in the same plane, the hooks 14 serving to securely grip andhold the sections against circumferential or other di placement withoutrequiring the spring clip to be unduly sprung or expanded beyond itsnormal die-holding position in the eilort to pass the hooks over theshort radial gap between two of the die sections.

In Figure 3 I have shown a ring formed without the right angle flange orretaining lip and in Figure 4: I have shown the sections assembled witha clip having no retaining hooks. However, I prefer to use the hookssince they tend to position the die sections firmly against each otherexcept where the gap is left at the open side of the clip. Moreover, thehooks receive the thrust of the expanding or'anchoring screw l6carricdby the stock so that there is less likelihood of producing any offsetlaterally from the plane of the die than if the screw has directengagement with the die sections themselves.

The ring 15 of the die stock is made so as to easily admit the diesections in assembled position and is provided with the main settingscrew 16 and any suitable number of peripheral holding screws 17 forfirmly securing the die within the stock.

The boring of the small holes 11 leaves I each die with a cutting edge19, the point of said cutting edge projecting very much fan ther inwardtoward the center of the die than the interior threaded portions of thedie between the holes 11; Owing to the fact that the threaded surfacesof the dies are formed on circles that are ofi'set laterally in twodirections from the center of the as sembled dieiithere is a sharp angleof divergen'ce produced between the curve of the ,threads and the circlepassing through the extreme cutting edges so as to afford amplysuficient clearance of the threaded surfaces of the die backer eachcutting edge.

It will be observed that the adjacent or opposed edges oi; the two diesections 1 53 located adjacent to th racial gap are bevelled to bearagainst the end of the set screw i6 and that the hooks let of theclipare formed to ride fiat against said bevelled surfaces.

What I claim is:

l. A die comprising a plurality of threadbearing sections separable onefrom another and a spring clip pe ipherally binding them together saidclip having an inturned hook at each end adapted to engage the opposedsurfaces of two adjacent sections, substantially as described. I

2. A die comprising a plurality of diecutting sections separable onefrom another the adjacent edges of two sections being bevelled, and aspring clip peripherally binding the sections together, the ends of theclip having inturned hooksengaging said bevelled ends, substantially asdescribed 3. A thread-cutting die comprising a plnrality of sectionsprovided with internally threaded cutting edges, means forpositioniug'and holding said SQClDlOIlF' in proper alignment comprisingan annular clip hav ing; inwardly turned hooks and having an inwardlyturned lip or flange adjacent to one side edge of the clip.substantially as described.

4. A thread-cutting die embracing in its construction a plurality ofsections formed with interior threaded cutting-edges and a holdinc: clipadapted to surround and hold said dies in. position said holding clipbeing provided on one side edge with an inturncil flange or lipwherebythe die. sections may be inserted from the opposite side) withoutdistorting or springing the clip beyond its normal. holding position.substantiallv as described. i

5. A thread-cuttin die comprising a pluralityoi" sections each having aninwardly proiectinc: thread-cutting edge, the internal. surface back ofeach cutting edge being: formed on a center that is laterallv ofiset tothe diametrical line interse ting the middle point of the peripheral arcof. the sedttioni substan ially as d escrihed.

6, A thread-cutting die embrac g in its construction pluralitv of sectorshaped sections whose inner threaded surfaces entend on circlesdescribed about differen centers that are laterally oil'set withrelation to the middle radius of each die section of the assembled die,substantiallv, as'described.

7. A threadmuttinc: die embracing in its construction a plurality ofseparable sections each of which is provided with inwardly projecting:cuttine ed es in advance of internal surfaces formed on a circledescribed about a center that is asymmetrically 'ofiset with relation tothe two radial ed ores of each die section in order to provide asufficient angle of clearance behind each cutting edge, substantially asdescribed.

8. A thread-cutting die embracing in its construction a plurality ofsector shaped die sections a circumferential holding clip comprising acontractible split ring provided with an inturned flange presenting aside thrust surface at right angles to the axis of the die therebyaffording a positive stop in contact with a side surface of each diesection, substantially as described.

9. A thread cutting die comprising a plurality of sectorseach of whichis formed with outside and inside circular surfaces, the inside circularface being described on a center that is asymmetrical to the outside circular surface whereby the sectors when assembled with their outersurfaces concentric will present interior cutting edges provided with anample clearance behind each cutting edge.

In testimony that I claim the foregoing inyention, I have hereunto setmy hand this 17th day of April, 1919.

CARL J PIHL.

